I want to track the time a user spends on a website without the user having the option to modify the time tracked? I want to include this with js. I don't have access to the backend of these sites because they aren't mine. The Script should send the time spent to the backend of my website.
So basically: Time tracking without being able to modify it and without access to the backend of the site.
Is there a way to make it 100% secure? If not, what's the most secure way for this?